vlib/v/checker/tests/comptime_assign_missing_mut_err.vv:13:4: error: `res` is immutable, declare it with `mut` to make it mutable
   11 |         val := doc.value(field.name)
   12 |         $if field.typ is string {
   13 |             res.$(field.name) = val.string()
      |             ~~~
   14 |         }
   15 |     }